1. Technical Field
The present invention relates to an image lens assembly. More particularly, the present invention relates to a compact image lens assembly applicable to electronic products.
2. Description of Related Art
In recent years, with the popularity of mobile products with camera functionalities, the demand of miniaturized optical lens systems is increasing. The sensor of a conventional photographing camera is typically a CCD (Charge-Coupled Device) or a CMOS (Complementary Metal-Oxide Semiconductor) sensor. As the advanced semiconductor manufacturing technologies have allowed the pixel size of sensors to be reduced and compact optical lens systems have gradually evolved toward the field of higher megapixels, there is an increasing demand for compact optical lens systems featuring better image quality.
A conventional compact optical lens system employed in a portable electronic product mainly adopts a structure of four-element lens such as the one disclosed in U.S. Pat. No. 7,869,142. Due to the popularity of mobile products with high-end specifications, such as smart phones and PDAs (Personal Digital Assistants), the requirements for high resolution and image quality of modern compact optical lens systems has been increasing significantly. However, the conventional four-element lens structure cannot satisfy these requirements of optical lens system with high-end specifications.
Although other conventional optical lens systems with five-element lens structure such as the ones disclosed in U.S. Pat. No. 8,000,031 enhance image quality, two lens elements of the optical lens system which closest to an image plane do not have positive refractive power, so that the incident angle of the off-axis light onto the two lens elements (a fourth lens element and a fifth lens element) cannot be effectively suppressed. Therefore, the high order aberration will be generated easily by the excessive refractive angle of the incident light and the Relative Illumination at a peripheral region of the image cannot be maintained.